U.S. Drought Monitor Update for February 12, 2019

According to the February 12, 2019, U.S. Drought Monitor, moderate to exceptional drought covers 13.6% of the United States, about the same as last week. Extreme and exceptional drought—the worst categories—cover 1.6% of the country for the third consecutive week.

During the week, a strong long-wave trough of low pressure held firm across the western contiguous United States in the upper levels of the atmosphere. Pacific weather systems moving through this trough intensified as they reached the central U.S., spreading above-normal precipitation across the northern Plains, Mississippi and Ohio River Valleys, and Great Lakes to East Coast.

Meanwhile, a strong upper-level low pressure system and surface front spun near the Hawaiian Islands, bringing above-normal precipitation—and snow in the higher elevations—to parts of these tropical islands. The western contiguous U.S. and Hawaiian troughs linked together to funnel an “atmospheric river” of tropical moisture into the western U.S., leaving areas of above-normal precipitation which continued to chip away at the western drought. The trough kept temperatures colder than normal across the western and central United States, while eastern parts of the country continued warmer than normal beneath a downstream ridge.

Areas that missed out on the precipitation this week included the southern High Plains to central Plains, where drought and abnormal dryness expanded, and the Southeast. With much of the heaviest precipitation this week falling in drought-free areas, little change occurred in the overall national drought picture.

Abnormal dryness and drought are currently affecting over 62 million people across the United States—about 19.9% of the country’s population.